x86/boot/compressed/64: Introduce sev_status

Introduce sev_status and initialize it together with sme_me_mask to have
an indicator which SEV features are enabled.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20201028164659.27002-2-joro@8bytes.org

diff --git a/arch/x86/boot/compressed/mem_encrypt.S b/arch/x86/boot/compressed/mem_encrypt.S
index dd07e7b..3092ae1 100644 (file)
--- a/arch/x86/boot/compressed/mem_encrypt.S
+++ b/arch/x86/boot/compressed/mem_encrypt.S
@@ -81,6 +81,19 @@ SYM_FUNC_START(set_sev_encryption_mask)
 
        bts     %rax, sme_me_mask(%rip) /* Create the encryption mask */
 
+       /*
+        * Read MSR_AMD64_SEV again and store it to sev_status. Can't do this in
+        * get_sev_encryption_bit() because this function is 32-bit code and
+        * shared between 64-bit and 32-bit boot path.
+        */
+       movl    $MSR_AMD64_SEV, %ecx    /* Read the SEV MSR */
+       rdmsr
+
+       /* Store MSR value in sev_status */
+       shlq    $32, %rdx
+       orq     %rdx, %rax
+       movq    %rax, sev_status(%rip)
+
 .Lno_sev_mask:
        movq    %rbp, %rsp              /* Restore original stack pointer */
 
@@ -96,5 +109,6 @@ SYM_FUNC_END(set_sev_encryption_mask)
 
 #ifdef CONFIG_AMD_MEM_ENCRYPT
        .balign 8
-SYM_DATA(sme_me_mask, .quad 0)
+SYM_DATA(sme_me_mask,          .quad 0)
+SYM_DATA(sev_status,           .quad 0)
 #endif